[PATCH RFC] bundle2: add a part for pointers to changegroups

[Mike Hommey]

On Tue, Sep 02, 2014 at 09:11:17PM +0200, Pierre-Yves David wrote:
> >- Bikeshed on the part name. I'm not entirely fond of "changegroupurl",
> >   and see next point.
> 
> I can suggest "seeother-changegroup" as a way to get you to love your
> original proposal.
> 
> >- I can think of another non-simple-url way to point to some other
> >   changegroup, that might be worth adding support for: a pointer to one
> >   or more changesets in a given repository. So instead of downloading a
> >   pre-generated bundle via http, the client would negociate a getbundle
> >   with that other repo. It's not entirely obvious how this could be
> >   useful, but it would allow us (Mozilla) to store, on S3, bundles of
> >   "patch sets" for our try server or review board, with a reference to
> >   the base it needs, which then can be applied on an existing clone of
> >   e.g. mozilla-central without having to use a full bundle (it would
> >   only have to get what it doesn't have) The question then becomes
> >   whether to create a new part for that, or to use the same part for
> >   both use cases and deal with the difference in the format.
> 
> This is a fairly interresting idea but probably deserve to be in a different
> part. We should also consider having the same kind of mechanism to download
> bundle2 archive (yes bundle2 inside a bundle2)

This, plus the thread on Sune's patch for changegroup2, makes me think
there could be a single new part that would be called 'external-bundle',
'import-bundle' or 'download-bundle', and would take an url to an
arbitrarily versioned bundle ; this would replace changegroupurl.

The "pointer to one of more changesets in a given repo" part would
indeed be better as a different part, at the very least because handling
it is going to be very different.

Mike